1. Field of the Invention
The present invention generally relates to storage technology and, more specifically, to power saving technology in storage systems, which include a plurality of storage apparatuses.
2. Description of Related Art
Various types of data are being handled by enterprises and individuals, and the amount data stored in storage devices is increasing rapidly due to the requirements to store electronic data for longer periods of time. Thus, in order to realize flexible scalability and reduction in management costs through uniform storage management, a storage area network configuration (primarily referred to as a SAN (Storage Area Network)) that connects a plurality of servers and a plurality of storage apparatuses with switches or hubs is used as the storage system. The progress of the storage system technology continuously demands more sophisticated functions and lower storage costs. With the emphasis on environmental issues in recent years, there are also requirements relating to energy efficiency of the data storage equipment.
In order to improve energy efficiency of the data storage systems, (energy saving) technology is disclosed for frequently monitoring the volume access from a host system using a storage extent (hereinafter also referred to as a “volume”) of a storage apparatus in a stand-alone storage apparatus, and migrating the disk apparatuses configuring the volume to an energy saving mode or turning off the power supply when there is no access from the host system for a prescribed period of time. In addition, technology is disclosed for diagnosing the disk apparatuses after the lapse of a prescribed period of time from the start of the energy saving process or when reaching a designated time in order to maintain the reliability regarding the disk apparatuses subject to the energy saving process. For instance, the power supply control technology of the disk apparatus in the storage apparatus disclosed in Japanese Patent Laid-Open Publication No. 2000-293314 (Patent Document 1) uses the power supply control of the disk apparatus provided to the storage apparatus according to the volume access frequency of the host system using the volume.